Lens clearing arrangement

ABSTRACT

A heatable optical element for a compound lens, the optical element being adapted to (i) provide a focusing function for the compound lens and (ii) be heated by resistive heating upon application of electricity to the heatable optical element. The compound lens including the heatable optical element may be employed in a camera, with the heatable optical element being the most distal optical element from a light sensor of the camera. A method for operating such a camera comprises detecting a present condition of the distal-most element and controlling application of electricity to control heating of the distal-most element in response to the detected present condition of the distal-most element.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 63/121,059 filed on Dec. 3, 2020, the contents of which are hereby incorporated by reference.

TECHNICAL FIELD

The present disclosure relates generally to camera lenses, and more specifically to removing ice and condensation from lenses used in cameras, e.g., thermal cameras.

BACKGROUND

Some of the main issues faced when designing a camera for use in a variety of climates and environments include icing and fogging in front of the camera. Icing and fogging of the camera lens may result in an inability to capture images. In particular, fogging or icing of lenses due to condensation in infrared cameras may result in reduced image quality. This inability to capture high quality images may be particularly significant when the camera is utilized for activities requiring real-time responses and accurate data, for example, in self-driving or assisted driving vehicles.

Some existing solutions for addressing icing and fogging include deploying a heating element near the lens and activating the heating element in response to icing or fogging. However, such deployment of this heating element requires additional energy and costs, as the heating element must be installed and maintained. There is also a reduction in image quality due to signal loss, e.g., by 8-10%. Further such heating elements, require enlarging the optical element in the camera. The heating elements do not provide uniform heating, take a long period of time to heat up, and often utilize more energy than required to remove the icing and fogging. In some implementations, the increase in size may make installation of a camera impractical.

Another existing solution includes providing a window for resistive heating. The window comprises: a transparent member having an outer edge, wherein the transparent member is made of a first material, wherein the first material is a low conductivity material; and at least one set of two conductive pads disposed on the outer edge of the transparent member and electrically coupled to at least one source of electricity, wherein each conductive pad is made of a second material, wherein matter disposed on the transparent member is removed via resistive heating when electricity is conducted from the at least one source through the at least one set of two conductive pads and the transparent member. While this is useful in some applications, using such a protective window adds an additional optical element, at an added cost, and may also cause a signal reduction, e.g., by 8-10%. Also, for wide field of view (FOV) lenses, the window needs to be bigger and hence more expensive due to raw material costs.

It would therefore be advantageous to provide a solution that would overcome the challenges noted above.

SUMMARY

A summary of several example embodiments of the disclosure follows. This summary is provided for the convenience of the reader to provide a basic understanding of such embodiments and does not wholly define the breadth of the disclosure. This summary is not an extensive overview of all contemplated embodiments, and is intended to neither identify key or critical elements of all embodiments nor delineate the scope of any or all embodiments. Its sole purpose is to present some concepts of one or more embodiments in a simplified form as a prelude to the more detailed description that is presented later. For convenience, the term some embodiments may be used herein to refer to a single embodiment or multiple embodiments of the disclosure.

Certain embodiments disclosed include a heatable optical element for a compound lens, the optical element being adapted to (i) provide a focusing function for the compound lens and (ii) be heated by resistive heating upon application of electricity to the heatable optical element.

Certain embodiments disclosed include a camera comprising a light sensor and a compound lens that supplies light to the sensor, the compound lens further comprising a distal-most element with respect to the sensor that is a lens that is transparent to at least one wavelength of light sensable by the light sensor, the distal-most element being exposed to an environment around the camera and being heatable upon application of electricity thereto.

Certain embodiments disclosed include a method for operating a camera comprising a light sensor and a compound lens that supplies light to the sensor, the compound lens further comprising a distal-most element with respect to the sensor that is a lens that is transparent to at least one wavelength of light sensable by the light sensor, the distal-most element being exposed to an environment around the camera and being heatable upon application of electricity thereto, the method comprising detecting a present condition of the distal-most element; and controlling application of electricity to control heating of the distal-most element in response to the detected present condition of the distal-most element.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features, and advantages of the disclosed embodiments will be apparent from the following detailed description taken in conjunction with the accompanying drawings.

FIG. 1 is a front view of a heatable lens according to an embodiment.

FIG. 2 is a side view of a heatable lens according to an embodiment.

FIG. 3 is an isometric view of an infrared camera including the heatable lens according to an embodiment.

FIG. 4 is an exploded view of a heatable lens, a flex PCB, and a connector utilized to describe various disclosed embodiments.

DETAILED DESCRIPTION

It is important to note that the embodiments disclosed herein are only examples of the many advantageous uses of the innovative teachings herein. In general, statements made in the specification of the present application do not necessarily limit any of the various claimed embodiments. Moreover, some statements may apply to some inventive features but not to others. In general, unless otherwise indicated, singular elements may be in plural and vice versa with no loss of generality. In the drawings, like numerals refer to like parts throughout several views.

The embodiments disclosed herein include an optical element for a compound lens, the optical element provides a focusing function as part of the compound lens optics and also provides resistive heating. The resistive heating may be controlled, e.g., in response to determined conditions such as environmental conditions. In some embodiments, the heatable lens is the first lens element of a compound lens of a camera. In other words, the heatable lens is the lens most distal from the image sensor of the camera. The material of which the lens is made may be a low conductivity material that is also transparent to the wavelength of interest. For example, for infra red radiation, and in particular to long wavelength infrared radiation, a material such as germanium may be employed to form the heatable lens. In some embodiments, germanium that has diamond-like carbon (DLC) coating may be employed. The germanium may be doped, e.g., N-type or P-type. The amount of doping may be used to control the conductivity of the germanium.

The heatable lens may have coupled thereto at least one set of two conductive pads, e.g., along an outer edge thereof. The conductive pads may be electrically couplable to at least one source of electricity. The conductive pads may be made of a different material than the heatable lens. When electricity is applied to the conductive pads, matter disposed on the heatable lens is removed via resistive heating as electricity is conducted from the at least one electricity source through the at least one set of two conductive pads via the heatable lens. The resistive heating of the heatable lens may be arranged to be sufficient to evaporate condensation or other liquids or solids disposed on the heatable lens. For example, the resistive heating may clear icing or fogging of the heatable lens.

The heatable lens may be further coupled to one or more sensors to detect its condition. For example, in some embodiments a temperature sensor may be attached to the heatable lens. The sensor output, e.g., an indication of the sensed temperature, may be coupled to a controller and the controller may control the supply of electricity to the heatable lens in response to the temperature indication. Thus, the controller may be configured to determine when an obstruction that can be cleared via heating is disposed on the heatable lens and, if so, to cause provision of electrical current to the conductive pads and through the heatable lens, thereby causing resistive heating to ensure that liquids and solids deposited or formed on the heatable lens, e.g., ice, fog, and so forth, are evaporated, thereby clearing the heatable lens.

Advantageously, the principles of the disclosed embodiments eliminate the need for an additional, separate element to remove ice and fog, reduce signal degradation, and reduce cost. Further advantageously, the form factor of the lens or a device in which it is included is not impacted by any required additional protective element. Due to the conduction of electricity through the heatable lens, the view of the camera may be rapidly cleared in seconds or fractions thereof.

The embodiments disclosed herein also include a camera apparatus. The camera apparatus comprises: at least one image sensor and a compound lens, the compound lens including at least one heatable lens disposed in the image stack as the first element thereof, i.e., the element that is most distal from the image sensor. The heatable lens may have coupled thereto at least one set of two conductive pads, e.g., along an outer edge thereof. The conductive pads may be electrically couplable to at least one source of electricity. The conductive pads may be made of a different material than the heatable lens. When electricity is applied to the conductive pads matter disposed on the heatable lens is removed via resistive heating when electricity is conducted from the at least one source through the at least one set of two conductive pads via the heatable lens. The heatable lens may be further coupled to one or more sensors to detect its condition. For example, in some embodiments a temperature sensor may be attached to the heatable lens. The sensor output, e.g., an indication of the temperature, may be coupled to a controller and the controller may control the supply of electricity to the heatable lens in response to the temperature indication. The controller may be internal to the camera or external thereto.

In an embodiment, the camera may be an infrared camera for use in, for example, capturing images or video from a vehicle such as a car. Using may be made of existing electrical components of the camera so as to allow for reduced energy consumption and reduced complexity of the camera components, thereby allowing for efficient heating and further miniaturization of camera.

FIG. 1 shows a front view of a heatable lens 110 for resistive heating according to an embodiment. The heatable lens 110 is shaped to provide an optical function as part of a compound lens, e.g., having some portion that is concave or convex or otherwise capable of bending or focusing light. Coupled to the heatable lens 110, e.g., attached thereon, are at least two conductive pads, e.g., conductive pads 120-1 and 120-2. In the manner shown in FIG. 1, heatable lens 110 has an outer edge 115. Each of the conductive pads 120-1 and 120-2 is disposed along the outer edge 115 such that least a portion of the heatable lens 110 is not covered by the conductive pads 120 and, thus, is exposed, thereby allowing light to pass through the exposed portion. In an illustrative implementation, the conductive pads 120-1 and 120-2 may be disposed on opposing portions of the heatable lens 110.

The conductive pads 120-1 and 120-2 conduct electricity from sources of electricity (not shown) connected thereto. During operation, electricity from the sources of electricity is passed from at least one of the conductive pads 120, e.g., conductive pad 120-1, to at least one other conductive pad 120, e.g., conductive pad 120-2, via the heatable lens 110 such that electricity conducted through the heatable lens 110 causes, via resistive heating of the heatable lens, evaporation of liquids, such as water droplets; solids, such as ice; or both, from the heatable lens 110. In an embodiment, the heatable lens 110 is made of a semiconductor material such as, but not limited to, N-type Germanium (GE) semiconductor.

The heatable lens 110 is sufficiently resistive to allow for resistive heating. To this end, in an embodiment, the heatable lens 110 has a resistivity which may be set, e.g., by manufacture, between 3 ohms centimeter (Ω·cm) and 40 Ω·cm, inclusive. This range of resistivities may be preferred in some applications, for example when using the heatable lens 110 in an infrared camera. It should be noted that other resistivities may be utilized for the heatable lens 110 depending on the size of the heatable lens 110, the power source providing electricity to the heatable lens 110, required temperatures for resistive heating, and other factors according to at least some disclosed embodiments.

It should be noted that two conductive pads 120-1 and 120-2 are shown in FIG. 1 merely for example purposes and without limitation on the disclosed embodiments. The heatable lens 110 as described herein is not limited to the particular configuration shown in FIG. 1, and may include any number of sets of conductive pads covering any portion of the heatable lens 110 without departing from the scope of the disclosure. Each set of conductive pads includes two conductive pads. The heatable lens 110 need not be round in shape.

Also shown in FIG. 1 is temperature sensor 130. Temperature sensor 130 is used to ascertain the temperature of the heatable lens 110 in order to determine the amount of heating necessary, and hence the amount of electricity that should be applied via conductive pads 120 at any one time. An output of temperature sensor 130, e.g., an indication of the temperature, may be coupled to a controller, not shown, which may be any suitable circuitry, and the controller may control the supply of electricity to the heatable lens 110 in response to the temperature indication. Thus, the controller may be configured to determine when an obstruction that can be cleared via heating is disposed on the heatable lens 110 and, if so, to cause provision of electrical current to the conductive pads 120 and through the heatable lens 110, thereby causing resistive heating to ensure that liquids and solids deposited or formed on the heatable lens 110, e.g., ice, fog, and so forth, are evaporated, thereby clearing the heatable lens 110.

The temperature sensor 130 should be located so as to avoid obstructing the view through heatable lens 110 as well as avoiding obstructing the view of other lenses of the compound lens of which heatable lens 110 is a part. It should be noted that temperature sensor 130 is shown in FIG. 1 merely for example purposes and without limitation on the disclosed embodiments. The temperature sensor 130 may include any number of portions or locations without departing from the scope of the disclosure. The temperature sensor 130 need not be shaped as shown in FIG. 1. In one embodiment temperature sensor 130 may be disposed on the exterior surface of heatable lens 110, i.e., the portion facing the exterior environment and is most distal from an image sensor when heatable lens 110 is part of a camera. In other embodiments the temperature sensor 130 may be located on the surface of heatable lens 110 that is not the exterior surface thereof or located elsewhere so long as a representation of the temperature at the most distal surface is determinable.

FIG. 2 shows a side view of the heatable lens 110. As shown in FIG. 2, the side view of heatable lens 110 includes a first outer surface 117 and a second outer surface 119. In the example shown in FIG. 2, heatable lens 110 is a convex lens. However, as noted, the lens may be of any suitable shape according to optical design specifications. Each of the outer surfaces 117 and 119 may be coated to, protect against damage to the heatable lens 110, reduce reflection, and the like. In an example implementation, the first outer surface 117 may be coated with a high durability coating to reduce scratching, and the second outer surface 119 may be coated with an anti-reflective (AR) coating to reduce glare. The high durability coating may be, but is not limited to, diamond-like carbon.

In an example implementation, the high durability coating can withstand exposure to adhesion, humidity, and moderate abrasion test conditions. In a further example, the adhesion test conditions may include pressing and removing an adhesive surface of cellophane tape to at least one of the outer surfaces 117 and 119 after coating. The humidity test may include placing the heatable lens 110 in a test chamber having a temperature of 120 degrees Fahrenheit, and 95-100% relative humidity, and the moderate abrasion test may include rubbing at least 50 strokes across each of at least one of surfaces 117 and 119 after coating.

FIG. 3 shows an isometric view of a camera 300 including the heatable lens 110 according to an embodiment. The camera 300 also includes a thermal core 310 and cables 320-1 and 320-2. The thermal core 310 may include, but is not limited to, a compound lens, which includes heatable lens 110, a light sensor, circuitry, and an electrical connector. Details of the components of the thermal core 310 are not shown, as they are not visible in that they are located inside of the housing of thermal core 310. The thermal core 310 does not require a separate heating element for defrosting or de-icing of its outermost lens element, which is heatable lens 110. Rather, an electrical current may be applied to the conductive pads 120, e.g., by corresponding electrodes or wires that may extend through cables 320-1 and/or 320-2, to pass through the heatable lens 110. Thus, the size and complexity of the camera 300 is reduced as compared to cameras implementing a heating element for defogging and de-icing that is independent of any lens element. Further, other thermal and electrical losses associated with utilizing a separate heating element, e.g., heat dissipation during conduction, electricity required to turn the heating element on or maintain the heating element being on, etc., may be minimized.

FIG. 4 is an example exploded view 400 of the heatable lens 110, a flex PCB 410, and a connector 420 that may be disposed in, for example, the camera 300 (FIG. 3). When deployed in the camera 300, the connector 420 may be electrically coupled to a power source of the camera 300 such that electricity may be conducted through the power source connector 420 to the flex PCB 410. When such electricity is conducted and the flex PCB 410 is electrically coupled to the conductive pads 120-1 and 120-2, electricity is conducted through the conductive pads 120-1 and 120-2 and the heatable lens 110, thereby causing the heatable lens 110 to warm up via resistive heating.

In one embodiment the flex PCB 410 may also include one or more wires coupled to temperature sensor 130. These wires may also pass through connector 420. In another embodiment, the temperature sensor 130 may be mounted on flex PCB 410.

Although the above has been described in terms of infrared, e.g., long wavelength infrared (LWIR), the principles of the disclosure may be applied to other wavelength ranges.

All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the principles of the disclosed embodiment and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. Moreover, all statements herein reciting principles, aspects, and embodiments of the disclosed embodiments, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents as well as equivalents developed in the future, i.e., any elements developed that perform the same function, regardless of structure.

It should be understood that any reference to an element herein using a designation such as “first,” “second,” and so forth does not generally limit the quantity or order of those elements. Rather, these designations are generally used herein as a convenient method of distinguishing between two or more elements or instances of an element. Thus, a reference to first and second elements does not mean that only two elements may be employed there or that the first element must precede the second element in some manner. Also, unless stated otherwise, a set of elements comprises one or more elements.

As used herein, the phrase “at least one of” followed by a listing of items means that any of the listed items can be utilized individually, or any combination of two or more of the listed items can be utilized. For example, if a system is described as including “at least one of A, B, and C,” the system can include A alone; B alone; C alone; A and B in combination; B and C in combination; A and C in combination; or A, B, and C in combination. 

What is claimed is:
 1. A heatable optical element for a compound lens, the optical element being adapted to (i) provide a focusing function for the compound lens and (ii) be heated by resistive heating upon application of electricity to the heatable optical element.
 2. The heatable optical element of claim 1, wherein the heatable optical element is included an item of the compound lens which includes a plurality of items and wherein the compound lens including the heatable optical element is deployed within a camera having a sensor, wherein light destined for the sensor enters a first end of the compound lens distal from the sensor and exits the compound lens at a second end proximal to the sensor, wherein the heatable optical element is the item of the compound lens that is most distal from the lens at which light destined for the sensor enters the compound lens.
 3. The heatable optical element of claim 2, wherein the sensor is an infrared sensor.
 4. The heatable optical element of claim 1, wherein the heatable optical element is a lens.
 5. The heatable optical element of claim 1, wherein the heatable optical element is formed of a material having a resistivity of between 3 ohms centimeter (Ω·cm) and 40 Ω·cm, inclusive.
 6. The heatable optical element of claim 1, wherein the heatable optical element is formed of a low conductivity material.
 7. The heatable optical element of claim 1, wherein the heatable optical element is transparent to a wavelength of interest.
 8. The heatable optical element of claim 1, wherein the heatable optical element is coupled to at least one sensor adapted to detect a condition of the heatable optical element.
 9. The heatable optical element of claim 1, wherein matter disposed on the optical heatable optical element is removed via evaporation caused by resistive heating of the heatable optical element upon application of electricity to the heatable optical element.
 10. The heatable optical element of claim 1, wherein the heatable optical element is formed of a material comprising germanium.
 11. The heatable optical element of claim 10, wherein the germanium is doped, wherein a type of the doping of the germanium is one the group consisting of: N-type doping and P-type doping.
 12. The heatable optical element of claim 1, further comprising at least one set of two conductive pads adapted to apply electricity to the optical element.
 13. The heatable optical element of claim 12, wherein each of the two conductive pads are located along an outer edge of the heatable optical element.
 14. The heatable optical element of claim 12, wherein each of the two conductive pads are adapted to be coupled to at least one source of electricity.
 15. The heatable optical element of claim 12, wherein each of the two conductive pads are made of a material different than a material from which the heatable lens is made.
 16. The heatable optical element of claim 1, wherein at least one surface of the heatable optical element is coated with at least one coating layer.
 17. The heatable optical element of claim 16, wherein each of the at least one coating layer comprises one of the group consisting of: a high durability coating and an anti-reflective coating.
 18. A camera comprising a light sensor and a compound lens that supplies light to the sensor, the compound lens further comprising a distal-most element with respect to the sensor that is a lens that is transparent to at least one wavelength of light sensable by the light sensor, the distal-most element being exposed to an environment around the camera and being heatable upon application of electricity thereto.
 19. The camera of claim 18, wherein the sensor is an infrared sensor.
 20. The camera of claim 18, further comprising: at least one sensor coupled to the distal-most element to detect its present condition; and a controller coupled to the sensor, the controller adapted to control application of electricity to the distal-most element based upon the detected present condition of the distal-most element.
 21. The camera of claim 20, wherein the present condition is one of the group consisting of: the presence of matter disposed on at least one surface of the distal-most element and the absence of matter disposed on at least one surface of the distal-most element.
 22. A method for operating a camera comprising a light sensor and a compound lens that supplies light to the sensor, the compound lens further comprising a distal-most element with respect to the sensor that is a lens that is transparent to at least one wavelength of light sensable by the light sensor, the distal-most element being exposed to an environment around the camera and being heatable upon application of electricity thereto, the method comprising: detecting a present condition of the distal-most element; and controlling application of electricity to control heating of the distal-most element in response to the detected present condition of the distal-most element.
 23. The method of claim 22, wherein the wherein the sensor is an infrared sensor.
 24. The method of claim 22, wherein the present condition is one of the group consisting of: the presence of matter disposed on at least one surface of the distal-most element and the absence of matter disposed on at least one surface of the distal-most element. 